The Secret of Saline

Wait a minute, isn't salt just salt? Dream on, Yankee dog.

Another column in this section recently had fun sampling the distinctive flavors of salts from around the world ("Salt, It's the New Pepper," Food Fetish, March 19). But why does salt from Thailand or Egypt taste different from the stuff sold here?

Despite the salt fad overcoming the nation's foodies, distinguishing between salts is nothing new. In ancient Roman times, according to Mark Kurlansky, author of Salt: A World History, Alexandria's salt was reputed to be the finest, and cooks in the West African Hausa empire kept palettes of different salts for different dishes. As far as we know, salt has been mined from the mountains and extracted from seawater for five thousand years or more. Three factors influence its flavor: chemical makeup (sodium versus potassium chloride, for example), crystalline structure and, of course, terroir -- minerals and other adulterants from the place where it was harvested.

Hawaiian red salt, for example, gets its flavor and color from clay, which is sometimes added after the salt is harvested from the sea. Smoked salt is just that, and it may replicate the flavor of the salt that the Celts extracted from the ashes of salt-marsh plants. Indus Foods in Berkeley carries a mined, highly odorous, black salt that smells like the sulfurous pits of hell and is often used -- sparsely -- in chaat. And the gray sea salt that Michael Chiarello hawks gets its color from the particulates in the Atlantic.

In yet another of those ironies that characterize our modern food supply, the less the salt is purified, the more expensive it now is. Fleur de sel, the "artisanally crafted" salt from Brittany that sells for up to $25 a pound, garnered its reputation during medieval times from the fact that skimming off the crystals that floated on the top of salt pools (the "salt flowers") instead of dredging them off the bottom produced a cleaner, less clayey salt. There's a good chance that Apicius and Taillevent would have preferred Morton's.

These days fleur de sel is prized for its delicate crystalline structure -- a crunch and a rush of saltiness that quickly dissipates. Sea salt and kosher salt are popular among chefs for their bigger, lighter crystals which, according to chemist Robert Wolke, the author of What Einstein Told His Cook, are produced by slower evaporation. They're neither less salty than table salt (just more loosely constructed) nor noticeably higher in minerals, as many producers claim: "You'd have to eat two tablespoons of [sea salt] to get the amount of iron, for example, contained in a single grape," he writes.

Linda Sikorsky of the Rockridge Market's Pasta Shop says the true use of these gourmet salts is to impart a subtle finish: "If you were to cook them into the stew you would lose all the nuances. In a focaccia bread, however, you'd use [a higher-end salt] at the end of the baking so the flavor of the salt would come through."

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